Residents of Ann Arbor and Surrounding Southeast Michigan Areas Can Seek Relief From Nature's Dealiest Gas: Radon. This New Hotline (734-971-0446) Allows Washtenaw County Residents Who Have Elevated Radon Levels to Receive Discounts on Radon Mitigation, Testing, Abatement Services, and Remediation Systems. Other Areas of Concern are Saline Dexter Brighton Ypsilanti Northville Novi and South Lyon.